send方法总是返回0

Question

I'm using swift_mailer to handle sending emails and I'm having a problem which is emails are not sent, and the return value of the send method is always equal to zero.

<kbd>app/config/config.yml</kbd>

swiftmailer:
   transport: smtp
   host:      <host>  # of the company
   username:  <username> # of the company
   password:  <password> # of the company
   port: 25

<kbd>app/config/config_test.yml</kbd>

swiftmailer:
    disable_delivery: true
    # disable_delivery: ~ # tried with this too

<kbd>Controller</kbd>

$mailer = $this->get('mailer');
$message = $mailer->createMessage()
    ->setSubject('You have Completed Registration!')
    ->setFrom('[e-mail]')
    ->setTo('[e-mail]')
    ->setBody(
        'hello world!!',
        'text/plain'
    )

var_dump($mailer->send($message, $failed), $failed); exit;

Output:

int(0)
array(0) {
}

I know that send returns the number of persons the email has been sent to. Why the email is never sent? Given that I'm sure of the only email address I'm trying to send to.

Update1:

I'd like to know how to debug this much further.

Answer 1

If you want to achieve a test environment mailer, do not use disable_delivery.
That completely disables swiftmailer's send.
Use

# app/config/config_dev.yml
swiftmailer:
      disable_delivery: false
      delivery_address: [e-mail] # some test or development email account